Inception is real.

Researchers at the Massachusetts Institute of Technology's Picower Institute for Learning manipulated the dreams of rats. The study underlined and built upon what we already know about the link between memory and sleep, but also could pave the way for the engineering of dreams.

Scientists already know that the hippocampus was hard at work during the night, replaying the day's events. That process is necessary for consolidating memories. Researchers did not know, however, whether those events could be manipulated by outside events.

The researchers, Daniel Bendor and Matthew Wilson, used two audio cues to manipulate the rats during the day. The rats quickly learned that one tone indicated that they could find food by turning left; the other tone indicated that they could find food by turning right. During this entire process with the maze, the researchers recorded their brain activity.

That night, the rats went to sleep. They also recorded their brain activity during the rest, determining that they were dreaming about the day's events in the maze. Then Bendor and Wilson played the audio cues that they had used earlier in the day as signals. Interestingly, the rats would then dream about the same portion of the maze that they had associated with the audio cue. Therefore, the study showed that dreams can be altered by reactivating certain memories when a person is asleep.

Researchers think that, in the future, this study can be used as a base to alter, enhance, or suppress dreams in people's and animals' sleep. The study authors say, "These results indicate that sleep replay can be manipulated by external stimulation and provide further evidence for the role of hippocampal replay in memory consolidation."

Scientists have studied the processes of dreaming extensively. Last week, Medical Daily reported that researchers found that it was possible for people to learn in their sleep. That study was conducted on 55 human participants in Israel, who were taught to associate certain audio cues with smells.

The study was published in the journal, Nature.